libs/DesignPattern/Bridge.pm

## --------------------------------------------------------------------------------
##  $Id: Bridge.pm,v 1.6 2003/02/09 16:22:51 joko Exp $
## --------------------------------------------------------------------------------
##  $Log: Bridge.pm,v $
##  Revision 1.6  2003/02/09 16:22:51  joko
##  + pseudo constructor mechanism via options
##
##  Revision 1.5  2003/01/31 01:19:50  root
##  + fixed: doesn't need Log::Dispatch any more, but uses it if available
##
##  Revision 1.4  2003/01/20 16:55:15  joko
##  + sub mixinPackage
##  + sub include
##
##  Revision 1.3  2002/12/16 19:57:12  joko
##  + sub unload
##
##  Revision 1.2  2002/12/15 02:06:15  joko
##  + feature to be able to specify module in non-perl-style when loading plugins: e.g. $process->load('Setup/Storage')
##
##  Revision 1.1  2002/12/13 21:46:29  joko
##  + initial check-in
##
## --------------------------------------------------------------------------------


package DesignPattern::Bridge;

use strict;
use warnings;

use base qw( DesignPattern::Object );

use Data::Dumper;

## ========   object inheritance   ========

# TODO / REFACTORING PROPOSAL
# leading from Data::Storage to code abstracted out into this module - DesignPattern::Bridge
#   - this is no inheritance and it doesn't have to be
#   - implement this module as a bridge to its sub-modules
#   - use the BridgePattern (http://c2.com/cgi/wiki?BridgePattern) 
#       Using patterns was already successfully done with Data::Storage::Handler
#       by implementing the AdapterPattern (http://c2.com/cgi/wiki?AdapterPattern)
#       with Perl's AUTOLOAD-mechanism
#   - try to use Perl's "tie" command to implement this functionality here instead of using AUTOLOAD!
#   - sub getChildNodes
#   - sub run

# 2003-02-11, joko: does this have anything in parallel with CPAN's Class::Inner?


# get logger instance
my $logger = eval { Log::Dispatch::Config->instance; };
  
my $meta;

## ========   object constructor   ========
sub new {
  my $invocant = shift;
  my $class = ref($invocant) || $invocant;
  my @args = ();
  @_ && (@args = @_);
  $logger->debug( __PACKAGE__ . "->new(@args)" ) if $logger;
  my $self = { @_ };

  # trace
    #print "class: $class", "\n";

  # create instance
  bless $self, $class;
  
  return $self;
}


## ========   method overrider   ========
  sub AUTOLOAD2 {
    
    my $self = shift;
    our $AUTOLOAD;
    
    ##print "AUTOLOAD\n";

    my $method = $AUTOLOAD;
    $method =~ s/^.*:://;
  
    $logger->debug( __PACKAGE__ . "->" . $method . "(@_)" . " (AUTOLOAD called, not dispatched)" ) if $logger;

    ## ->DESTROY would - if not declared - trigger an AUTOLOAD also
    return if $method =~ m/::DESTROY$/;
  
##    if ($self->_filter_AUTOLOAD($method)) {
##      $self->_accessStorage();
##      $self->{STORAGEHANDLE}->$method(@_);
##    }
    
  }

  sub _getPluginPackage {
    my $self = shift;
    my $modulename_load = shift;

    # substitute slashes through double double-colons to load modules perl-style
    $modulename_load =~ s/\//::/g;
    
    # build full package name
    my $self_classname = ref $self;
      # name
      my $package = $modulename_load;
      
      # if package is absolute, cut away prefix ('/' or '::')
      if ($package !~ s/^:://) {
        # else: prefix with base classname if above name is relative (lacks of '/' or '::')
        $package = $self_classname . '::' . $package 
      }
    
    return $package;
  }
  
  sub load {

    my $self = shift;
    my $modulename_load = shift;

    my $options = shift;

    my $self_modulename = ref $self;
    my $package = $self->_getPluginPackage($modulename_load);
    
    if ($meta->{loaded}->{$package}) {
      return 1;
    }
    
    #$logger->info( __PACKAGE__ . "->load: $package" ) if $logger;
    #$logger->info( __PACKAGE__ . "->load: $self_modulename" ) if $logger;
    $logger->debug( $self_modulename . "->load: $package\t[via " . __PACKAGE__ . "]" ) if $logger;

    # this is the module testing phase - use mixin doesn't seem to propagate errors by default
    eval("use $package;");
    if ($@) {
      $meta->{loaded}->{$package} = 0;
      # include caller information
      my @caller = caller;
      my $caller_msg = $caller[1] . ':' . $caller[2];
      my $msg =  __PACKAGE__ . "->load: $@ ($caller_msg)";
      if ($logger) {
        $logger->error($msg);
      } else {
        print $msg, "\n";
      }
    }

#print "ref-1: ", ref $self, "\n";
#print "ref-2: ", ref $self::SUPER, "\n";
    
    # V1:
    #bless $self, $package;

    # V2:

    # switch into foreign package and prepare for mixin
    $self->mixin_prepare($package);

    # switch into local package (scope which uses DesignPattern::Bridge) and mixin plugin-module
    $self->mixin_do($package);

    if (my $method = $options->{method}) {
      $self->$method();
    }

    return 1;
    
  }

  # TODO: maybe refactor to DesignPattern::Object? what about the '$logger'?
  sub mixin_prepare {
    my $self = shift;
    my $package = shift;
    my $self_classname = ref $self;
    eval("package $package; use mixin::with '$self_classname';");

    # FIXME: --- this is redundant ---
    if ($@) {
      $meta->{loaded}->{$package} = 0;
      $logger->error( __PACKAGE__ . "->load: $@" ) if $logger;
    } else {
      $meta->{loaded}->{$package} = 1;
    }
    # FIXME: --- this is redundant ---

  }

  sub mixin_do {
    my $self = shift;
    my $package = shift;
    # switch into foreign package and mixin plugin-module
    my $self_classname = ref $self;
    eval("package $self_classname; use mixin '$package';");
    #eval("use mixin_all '$package';");

    # FIXME: --- this is redundant ---
    if ($@) {
      $meta->{loaded}->{$package} = 0;
      $logger->error( __PACKAGE__ . "->load: $@" ) if $logger;
    } else {
      $meta->{loaded}->{$package} = 1;
    }
    # FIXME: --- this is redundant ---

  }

  sub unload {

    my $self = shift;
    my $modulename_unload = shift;

    my $package = $self->_getPluginPackage($modulename_unload);
    
    if ($meta->{loaded}->{$package}) {
      $meta->{loaded}->{$package} = 0;
      my $where = __PACKAGE__ . ':' . __LINE__;
      $logger->debug( __PACKAGE__ . "->unload: FIXME: DESTROY object is not implemented at '$where'." ) if $logger;
    }

  }


  sub boot {
    my $self = shift;
    $self->_abstract_function('boot');
  }
  
  sub include {
    my $self = shift;
    my $includefile = shift;
    my $package = shift;
    # TODO: do better error-detection here / prevent dies under all circumstances!
    require $includefile;
    $self->mixinPackage($package) if $package;
  }

1;
__END__
1	joko	1.1	## --------------------------------------------------------------------------------
2	joko	1.7	## $Id: Bridge.pm,v 1.6 2003/02/09 16:22:51 joko Exp $
3	joko	1.1	## --------------------------------------------------------------------------------
4	joko	1.2	## $Log: Bridge.pm,v $
5	joko	1.7	## Revision 1.6 2003/02/09 16:22:51 joko
6			## + pseudo constructor mechanism via options
7			##
8	joko	1.6	## Revision 1.5 2003/01/31 01:19:50 root
9			## + fixed: doesn't need Log::Dispatch any more, but uses it if available
10			##
11	root	1.5	## Revision 1.4 2003/01/20 16:55:15 joko
12			## + sub mixinPackage
13			## + sub include
14			##
15	joko	1.4	## Revision 1.3 2002/12/16 19:57:12 joko
16			## + sub unload
17			##
18	joko	1.3	## Revision 1.2 2002/12/15 02:06:15 joko
19			## + feature to be able to specify module in non-perl-style when loading plugins: e.g. $process->load('Setup/Storage')
20			##
21	joko	1.2	## Revision 1.1 2002/12/13 21:46:29 joko
22			## + initial check-in
23			##
24	joko	1.1	## --------------------------------------------------------------------------------
25
26
27			package DesignPattern::Bridge;
28
29			use strict;
30			use warnings;
31
32			use base qw( DesignPattern::Object );
33
34	joko	1.2	use Data::Dumper;
35
36	joko	1.1	## ======== object inheritance ========
37
38	joko	1.7	# TODO / REFACTORING PROPOSAL
39			# leading from Data::Storage to code abstracted out into this module - DesignPattern::Bridge
40	joko	1.1	# - this is no inheritance and it doesn't have to be
41			# - implement this module as a bridge to its sub-modules
42			# - use the BridgePattern (http://c2.com/cgi/wiki?BridgePattern)
43			# Using patterns was already successfully done with Data::Storage::Handler
44			# by implementing the AdapterPattern (http://c2.com/cgi/wiki?AdapterPattern)
45			# with Perl's AUTOLOAD-mechanism
46			# - try to use Perl's "tie" command to implement this functionality here instead of using AUTOLOAD!
47			# - sub getChildNodes
48			# - sub run
49
50	joko	1.7	# 2003-02-11, joko: does this have anything in parallel with CPAN's Class::Inner?
51
52
53	joko	1.1	# get logger instance
54	root	1.5	my $logger = eval { Log::Dispatch::Config->instance; };
55	joko	1.1
56	joko	1.3	my $meta;
57	joko	1.1
58			## ======== object constructor ========
59	joko	1.7	sub new {
60			my $invocant = shift;
61			my $class = ref($invocant) \|\| $invocant;
62			my @args = ();
63			@_ && (@args = @_);
64			$logger->debug( __PACKAGE__ . "->new(@args)" ) if $logger;
65			my $self = { @_ };
66
67			# trace
68	joko	1.1	#print "class: $class", "\n";
69	joko	1.7
70			# create instance
71			bless $self, $class;
72
73			return $self;
74			}
75	joko	1.1
76
77			## ======== method overrider ========
78			sub AUTOLOAD2 {
79
80			my $self = shift;
81			our $AUTOLOAD;
82
83			##print "AUTOLOAD\n";
84
85			my $method = $AUTOLOAD;
86			$method =~ s/^.*:://;
87
88	root	1.5	$logger->debug( __PACKAGE__ . "->" . $method . "(@_)" . " (AUTOLOAD called, not dispatched)" ) if $logger;
89	joko	1.1
90			## ->DESTROY would - if not declared - trigger an AUTOLOAD also
91			return if $method =~ m/::DESTROY$/;
92
93			## if ($self->_filter_AUTOLOAD($method)) {
94			## $self->_accessStorage();
95			## $self->{STORAGEHANDLE}->$method(@_);
96			## }
97
98			}
99	joko	1.3
100			sub _getPluginPackage {
101			my $self = shift;
102			my $modulename_load = shift;
103
104			# substitute slashes through double double-colons to load modules perl-style
105			$modulename_load =~ s/\//::/g;
106
107			# build full package name
108			my $self_classname = ref $self;
109	joko	1.7	# name
110			my $package = $modulename_load;
111
112			# if package is absolute, cut away prefix ('/' or '::')
113			if ($package !~ s/^:://) {
114			# else: prefix with base classname if above name is relative (lacks of '/' or '::')
115			$package = $self_classname . '::' . $package
116			}
117
118	joko	1.3	return $package;
119			}
120	joko	1.1
121			sub load {
122
123			my $self = shift;
124	joko	1.3	my $modulename_load = shift;
125	joko	1.1
126	joko	1.6	my $options = shift;
127
128	joko	1.4	my $self_modulename = ref $self;
129	joko	1.3	my $package = $self->_getPluginPackage($modulename_load);
130	joko	1.1
131	joko	1.3	if ($meta->{loaded}->{$package}) {
132			return 1;
133			}
134	joko	1.2
135	root	1.5	#$logger->info( __PACKAGE__ . "->load: $package" ) if $logger;
136			#$logger->info( __PACKAGE__ . "->load: $self_modulename" ) if $logger;
137			$logger->debug( $self_modulename . "->load: $package\t[via " . __PACKAGE__ . "]" ) if $logger;
138	joko	1.1
139			# this is the module testing phase - use mixin doesn't seem to propagate errors by default
140			eval("use $package;");
141			if ($@) {
142	joko	1.3	$meta->{loaded}->{$package} = 0;
143	joko	1.2	# include caller information
144			my @caller = caller;
145			my $caller_msg = $caller[1] . ':' . $caller[2];
146	root	1.5	my $msg = __PACKAGE__ . "->load: $@ ($caller_msg)";
147			if ($logger) {
148			$logger->error($msg);
149			} else {
150			print $msg, "\n";
151			}
152	joko	1.1	}
153
154			#print "ref-1: ", ref $self, "\n";
155			#print "ref-2: ", ref $self::SUPER, "\n";
156
157			# V1:
158			#bless $self, $package;
159
160			# V2:
161	joko	1.7
162			# switch into foreign package and prepare for mixin
163			$self->mixin_prepare($package);
164
165			# switch into local package (scope which uses DesignPattern::Bridge) and mixin plugin-module
166			$self->mixin_do($package);
167	joko	1.6
168			if (my $method = $options->{method}) {
169			$self->$method();
170			}
171	joko	1.4
172			return 1;
173
174			}
175
176			# TODO: maybe refactor to DesignPattern::Object? what about the '$logger'?
177	joko	1.7	sub mixin_prepare {
178			my $self = shift;
179			my $package = shift;
180			my $self_classname = ref $self;
181			eval("package $package; use mixin::with '$self_classname';");
182
183			# FIXME: --- this is redundant ---
184			if ($@) {
185			$meta->{loaded}->{$package} = 0;
186			$logger->error( __PACKAGE__ . "->load: $@" ) if $logger;
187			} else {
188			$meta->{loaded}->{$package} = 1;
189			}
190			# FIXME: --- this is redundant ---
191
192			}
193
194			sub mixin_do {
195	joko	1.4	my $self = shift;
196			my $package = shift;
197			# switch into foreign package and mixin plugin-module
198	joko	1.3	my $self_classname = ref $self;
199	joko	1.1	eval("package $self_classname; use mixin '$package';");
200			#eval("use mixin_all '$package';");
201	joko	1.7
202			# FIXME: --- this is redundant ---
203	joko	1.1	if ($@) {
204	joko	1.3	$meta->{loaded}->{$package} = 0;
205	root	1.5	$logger->error( __PACKAGE__ . "->load: $@" ) if $logger;
206	joko	1.3	} else {
207			$meta->{loaded}->{$package} = 1;
208	joko	1.1	}
209	joko	1.7	# FIXME: --- this is redundant ---
210
211	joko	1.3	}
212
213			sub unload {
214
215			my $self = shift;
216			my $modulename_unload = shift;
217
218			my $package = $self->_getPluginPackage($modulename_unload);
219	joko	1.1
220	joko	1.3	if ($meta->{loaded}->{$package}) {
221			$meta->{loaded}->{$package} = 0;
222			my $where = __PACKAGE__ . ':' . __LINE__;
223	root	1.5	$logger->debug( __PACKAGE__ . "->unload: FIXME: DESTROY object is not implemented at '$where'." ) if $logger;
224	joko	1.3	}
225
226	joko	1.1	}
227	joko	1.3
228	joko	1.1
229			sub boot {
230			my $self = shift;
231			$self->_abstract_function('boot');
232	joko	1.4	}
233
234			sub include {
235			my $self = shift;
236			my $includefile = shift;
237			my $package = shift;
238			# TODO: do better error-detection here / prevent dies under all circumstances!
239			require $includefile;
240			$self->mixinPackage($package) if $package;
241	joko	1.1	}
242
243			1;
244	joko	1.7	__END__
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